Updated on September 2, 2025.
Roughly 1 in 8 U.S. adults say they’ve taken a GLP-1 at some point, a class of prescription weight loss drugs used to help manage diabetes, heart disease, obesity, liver disease, and obstructive sleep apnea (OSA), according to a May 2024 poll by the KFF, a U.S. health policy organization. This includes 6 percent of adults who are currently on one of these drugs. Awareness about GLP-1s has also skyrocketed since the first one (exenatide) was approved by the U.S. Food and Drug Administration (FDA) in 2005. The KFF poll found that about one-third of adults say they’ve heard “a lot” about them, up from 19 percent a year earlier.
Beyond the headlines however, it’s important to understand how these drugs work. While shown to be highly effective, they may cause side effects. Researchers are still working to understand the long-term risks of these medications. Side effects vary from one person to the next. And generally, the higher the dose, the great the risk.
But for many people, the benefits of taking a GLP-1 outweigh potential downsides.
How do GLP-1s work?
GLP-1 (glucagon-like peptide-1) is a hormone. It’s made in the small intestine, and it has a few important jobs, including:
- It helps control blood sugar levels by triggering the release of insulin from the pancreas. Insulin is another hormone that helps move sugar from the blood into cells where it can be used for energy.
- It blocks the release of glucagon. Glucagon is another hormone that triggers the release of stored sugar (glycogen) from the liver, causing blood sugar levels to rise.
- It slows digestion, which reduces the amount of sugar the body releases into the bloodstream.
- It affects areas of the brain involved in hunger and satiety, controlling appetite and promoting a feeling of fullness.
GLP-1s are also called GLP-1 agonists. Agonists are substance that mimic a hormone and produce similar responses in the body. So, these drugs act like GLP-1 and help lower blood sugar levels by triggering the release of insulin. They also help people lose weight by slowing digestion and making people feel more full and less hungry.
What are the most common side effects of GLP-1s?
The most commonly reported side effects of GLP-1s are digestive issues, such as:
- Nausea
- Vomiting
- Diarrhea
- Constipation
- Bloating
- Indigestion
- Heartburn
There are some lifestyle adjustments that can help ease or prevent these issues, such as:
- Eat slowly and chew your food well.
- Listen to your body and stop eating when you start to feel full.
- Eat smaller, more frequent meals and/or reduce the size of your food portions.
- Stay upright for at least 30 minutes after eating.
- Avoid being very active for at least 30 minutes after eating.
- For nausea and diarrhea, choosing bland, low-fat, and easy-to-digest foods like plain crackers, bananas, and rice can help. Having a beverage that contains mint, or ginger can also ease nausea.
- Eating high-fiber foods, like fruits, vegetables, and whole grains, can help prevent or manage constipation. You can also ask your HCP about fiber supplements or other over-the-counter remedies (such as osmotic laxatives) that soften stool and helps it move through the intestines.
- Drink plenty of fluids to stay well hydrated. This is particularly important if you are vomiting or have diarrhea. Talk to your HCP about how much water you should be drinking daily.
- Avoid or limit your intake of greasy, spicy, or fatty foods. It’s also wise to limit alcohol and avoid carbonated beverages.
Can blood sugar drop too low?
Since GLP-1s work to lower blood sugar levels, it is possible for blood sugar to drop too low. But this is a rare side effect when GLP-1s are taken alone. The risk increases if they are taken with other diabetes medications, including insulin.
About two hours after eating a meal, a normal blood sugar level is between 70 and 100 mg/dL. A level lower than 70 mg/dL is considered low or hypoglycemia. A very low level can be life-threatening. Signs of low blood sugar include:
- Feeling shaky or trembling
- Feeling nervous or anxious
- Sweating or chills
- Irritability
- Confusion or trouble thinking
- Fast heartbeat
- Feeling lightheaded or dizzy
- Hunger
- Nausea
- Weakness
- Blurry vision
- Pale skin
Drinking some juice or eating a “fast-acting” carbohydrate, such as a small banana, can help increase blood sugar levels. Fast-acting carbs are typically simple carbs with little or no fat, fiber, or protein (which would take longer for the body to process). As a result, they help increase blood sugar more quickly.
Many people start feeling the signs of hypoglycemia before their blood sugar drops too low. This can help them take action to help keep it steady. Other ways to prevent low blood sugar:
- Monitor your blood sugar levels regularly and carefully as directed by your healthcare provider (HCP).
- Stick to a regular meal schedule.
- Plan meals and workouts around medications.
- Keeping fast acting carbs or healthy snacks on hand.
- Track your diet in an app or food journal.
- Do not drink alcohol on an empty stomach.
What is “Ozempic face”?
One of the most widely reported GLP-1 side effects was dubbed "Ozempic face”—a term used to describe sagging and wrinkled skin. But this effect is not specific to GLP-1s. It can occur any time rapid weight loss occurs. For some, the skin doesn’t have as much time to retract as it would with more gradual weight loss. In other cases, elastin (the protein fibers that make the skin elastic) may have become weakened or damaged over time.
Weight loss is not limited to certain parts of the body, like the belly. It occurs everywhere, including the face. So, when this happens very quickly, the following can happen to the face:
- The eyes and cheeks may appear hollowed or sunken
- The lips may become thinner
- The skin can sag or develop wrinkles
- Jowls may develop around the jaw and neck
These effects may be avoided with more gradual weight loss. More severe cases that affect people’s quality of life or mental well-being can be improved with plastic surgery.
Some steps people can take to help prevent or minimize these issues:
- Eat adequate amounts of protein to help build or maintain muscle mass
- Wear sunscreen daily to protect the skin from the sun’s harmful UV rays
- Drink plenty of water to stay well-hydrated
- Use skincare products that promote collagen production
Can someone be allergic to a GLP-1?
Another possible side effect of GLP-1s is itchiness or redness at the injection site. This could signal an allergic reaction to the drug. Anyone who develops these symptoms should let their HCP know right away.
It’s important to be aware of warning signs of a life-threatening allergic reaction known as anaphylaxis. Anaphylaxis is a medical emergency. Anyone who develops the following symptoms should call 911 or go to the nearest emergency room right away:
- Trouble breathing or swallowing
- Wheezing
- Hives
- Skin rash
- Belly pain
- Tightness in the chest
- Feelings of doom or dread
Are there other more rare or serious GLP-1 side effects?
Rarely, people on a GLP-1 may experience:
- Gallstones or other gallbladder issues
- Pancreatitis (painful inflammation of the pancreas)
- Sudden kidney damage
- Gastroparesis (stomach emptying is very slow or stopped)
- Bowel obstruction (a blockage in the intestines that prevents food from passing through)
- Ileus (paralyzed intestines, or the movement of food and waste is halted even without a physical obstruction)
Anyone who experiences the following signs of one of these more serious complications should contact their HCP right away:
- Severe vomiting and diarrhea
- Severe belly pain or tenderness
- Inability to pass gas or poop
- Yellow skin color
- Very dark urine or less frequent urination
Keep in mind, GLP-1 side effects are more likely to occur early on, when people first start taking the medication. They are also more likely to occur at higher doses. Those who experience any uncomfortable or worrisome side effects should let their HCP know. It may be possible to switch to a different GLP-1 drug or adjust the dosage of the current medication.
